Myoporum insulare - Boobialla

Click image to enlarge

Myoporum insulare – Boobialla

This plant is also known as the Blueberry Tree because of its mature purple blue berries (green when immature). It is a very widespread plant being distributed in all southern States from Shark Bay in WA to the mid-coastal area of NSW. However it is not particularly common in WA and usually only encountered in widely spaced small colonies.

Myoporum insulare is mainly a coastal or near coastal species and locally grows in sandy moist calcareous soils close to brackish water, especially along the lower (near coastal) reaches of rivers and creeks. These areas are normally quite exposed, thereby requiring this species to form a compact spreading shrub to 2.5 metres (around 8’) in height, although it is known to reach over twice that in more sheltered areas elsewhere.

It is possible to confuse this plant with another local species Myoporum tetrandrum, but the leaves (on flowering branches) of that species are around 1 cm (½”) in width, whereas the leaves of Myoporum insulare are wider to over 2 cm (1”). The leaves of M. insulare are also much thicker. The habitat differs too, with Myoporum tetrandrum favouring more sheltered locations with less brackish water and heavier non-calcareous soils.

The flowers have different features too, with Myoporum insulare having large anthers on short filaments (stalks), contrasting with M. tetrandrum, which has small anthers but on long filaments. The internal corolla (floral tube and petals) can be spotted or unspotted, so this aspect is not a reliable identification feature; they bloom anytime from July to February depending on local weather conditions. http://esperancewildflowers.blogspot.com.au/2013/12/myoporum-tetrandrum-boobialla.html

The genus Myoporum is part of the large Scrophulariaceae family, but some references may still use the previous family name of Myoporaceae.

Myoporum tetrandrum - Boobialla

Click image to enlarge

Myoporum tetrandrum - Boobialla

The Myoporum genus is not restricted to Australia with various species widespread in the Pacific Islands (including NZ), and various Asian countries encompassing some Japanese territories and even China. However most of the 30 odd species are found only in Australia. Myoporum tetrandrum is endemic to WA, occurring mainly in near coastal environments from Kalbarri (N of Perth) to Israelite Bay (E of Esperance).

Around Esperance it is reasonably common in boggy ground along creeks and seepage zones and is often encountered growing with tall Melaleuca and Sedge spp. Here it can form open shrubs to 3 metres (10’) in height, or lower rambling forms to half that height that protrude above compact sedge colonies. The white flowers with purple spots can bloom for extended periods between May and January, but it is the foliage that distinguish the species.

Although the leaves can vary considerably in size, they are finely toothed especially in the upper half, plus gradually taper to the base. The only other local species M. tetrandrum could be confused with, is Myoporum velutinum a rare species (east of Cape Le Grand) with hairy foliage and the only species to have hairs on the outer corolla (petals and floral tube).

A study of Myoporum tetrandrum published in the Australian Veterinary Journal (Vol. 54, Issue 6, June 1978) found that the essential oils in the foliage were toxic to stock and eventuated in lesions forming on their livers. The common name of Boobialla is thought to be a Tasmanian Aborigine word for Myoporum plants, but was also used to describe an Acacia species with edible seeds, which some references have incorrectly applied to Myoporum tetrandrum that is not edible.

The genus Myoporum is part of the large Scrophulariaceae family, but some references may still use the previous family name of Myoporaceae.

Myoporum turbinatum – Scrophulariaceae (Myoporaceae)

Click image to enlarge

Myoporum turbinatum – Scrophulariaceae (Myoporaceae)

Under the new classification system adopted by the Western Australian Herbarium, the well known family Myoporaceae that includes the large Eremophila genus, has now been absorbed into Scrophulariaceae, which is a pity if for no other reason than the former was easier to pronounce, let alone remember. This particular species has a common name of Salt Myoporum, because it is at times found near saline depressions.

Plants in the genus Myoporum tend to be more coastal than Eremophila, which is mainly found well inland. They are taxonomically separated by the shape of their opened anthers, with Myoporum being kidney shaped, whilst Eremophila more arrow like. However, in most instances the flower shape of Myoporum is regular (radially symmetrical) and Eremophila two lipped (irregular or zygomorphic).

Myoporum turbinatum is a very rare species, known only from a small area NE of Esperance generally within a couple hundred metres of small saltlakes. I know it from four very restricted colonies, but all are only a few kilometres apart and either on the disturbed edge of a limestone/gravel road, or in small roadside limestone quarries where road making material was extracted. These quarries are ripped by the bulldozers after operations to permit regrowth, which they generally do most successfully and provide excellent areas to look for wildflowers, although ephemeral species do not do as well.

In one quarry there had been several dozen Myoporum turbinatum plants to 4 metres (around 12’) in height, which had been labelled, presumably to check on their progress. Of these a number had died, but most were still hanging on, if only by a few centimetres/inches of growth at their tips, but going on their current state of health will not survive much longer. There was no germination to replenish the colony, but their seed would have fallen to the ground to await a fire or further soil disturbance.

Close to ten years ago, I found a few plants to 1.5 metres (5’) in another limestone quarry that were quite bushy, so the very leggy appearance I would suggest is due to age and periodic dry conditions. So depending on the luck of the draw, if plants germinate in a good (moist) year, with the following year also of reasonable rainfall, growth habit can be remarkably different. Three young plants, also to 1.5 metres and growing on the edge of a road were regarding growth habit, somewhere between (see photograph above). Interestingly, ten years ago Myoporum turbinatum plants were growing in the same place, although they had died possibly during road improvements, these later plants had probably grown from their seed.

The species name of turbinatum refers to the top-shaped fruits, which are produced in number, even on the shortest of live branches, so the lack of insect pollination and seed production is not a reason for the rarity of this plant. The leaves are around 5 cm (2”) in length, quite resinous and distinctly warty. The flowers are white and about the size of your little fingernail and over the year are progressively produced along flowering stems (except winter or very dry periods).

Myoporum turbinatum has a Conservation Status: Declared Rare, which means it has been adequately searched for, and is deemed to be either rare, in danger of extinction, or in need of special protection.